Intermanual transfer of sensorimotor memory for grip force when lifting objects: the role of wrist angulation

To investigate the mechanisms underlying the intermanual transfer of sensorimotor memory when lifting an object.

Twenty healthy subjects grasped and lifted an object with constant mechanical properties with the right hand (RH) first and then with the left hand (LH). Ten of the subjects lifted the object with the RH in a regular wrist angulation (WA), followed by lifts with the LH in a regular WA. The remaining 10 subjects lifted the object with the RH in a hyper-flexed WA, followed by lifts with the LH in a regular WA.

Subjects generated greater peak grip force (GF) rates, grip and lift forces when lifting the object with the wrist in a regular WA compared to lifts with the wrist in hyper-flexion. Importantly, subjects transferred the predictive scaling of GF from the RH to the LH, regardless of the WA.

Biomechanical properties of the object do not seem to be used by the CNS as a first line information to evaluate GF when handling an object or transferring information about the grasp to the opposite hemisphere.

The predictive scaling of GF rather reflects an internal sense of effort than an internal representation of the mechanical object properties.